Closed Loop Recycling of Composite Waste Streams into High Performance Aligned Short Fiber Composites

Dr. Dirk Heider | University of Delaware

WP20-1483

Objective

This effort addresses two environmental impact areas: closed-loop recycling and reuse of high value carbon fiber from prepreg waste streams (process scrap, expired shelf life material) and reduction of manufacturing scrap rates. Both are enabled using a recently developed highly aligned short fiber technology. This effort will demonstrate closed loop recycling of carbon fibers with recycled material forms achieving equivalent mechanical performance to the original continuous fiber systems. In parallel, manufacturing scrap reduction will be demonstrated as the short fiber material exhibit in-plane stretchability and forms like metals to complex part geometries, thus significantly reducing or possibly eliminating draping challenges, which lead to high scrap rates with current prepreg processes. Lifecycle cost analysis will be performed to quantify cost, environmental and health impact benefits.

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Technical Approach

Under a recent Defense Advanced Research Projects Agency (DARPA)-funded program, a patent-pending short fiber alignment and preforming process (called Tailorable Universal Feedstock for Forming [TuFF]) has been developed at University of Delaware – Center for Composite Materials (UD-CCM) creating composite parts with high fiber volume fraction and equivalent properties to continuous fiber composites. The approach allows 1) recycling of uncured prepreg or waste fiber material, 2) reduction/elimination of manufacturing scrap generated during part production, and 3) recycling/reuse of carbon fiber composite materials. The recycled fiber material will be recovered in discontinues form and reprocessed with the TuFF system to create high fiber volume fraction parts (~60%) with 100% property translation compared to continuous fiber composites. The short fiber microstructure also permits in-plane deformation or stretch similar to metals allowing forming of complex geometry parts. This eliminates significant manufacturing scrap from ply patterns needed to produce complex preforms during conventional composites manufacturing. This project will demonstrate the recycling methodologies for a variety of composite materials from different waste streams and demonstrate the improved environmental and value proposition through lifecycle analysis.

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Benefits

The ability to create highly aligned short fiber preforms and resultant composites that demonstrate equivalent mechanical performance to continuous fiber prepreg systems, changes the paradigm for carbon fiber recycling and reuse. Process and manufacturing scrap from all sources starting with fiber scrap during fiber production, prepreg scrap to scrap from part production can now be converted into high value short carbon fiber preforms or prepreg for reuse in the same application space. This can eliminate hazardous waste issues with prepreg scrap or expired materials, as the fibers can be extracted (e.g. cure and pyrolysis) and reused. Recycled fiber costs are significantly lower than certified continuous fiber, thus initial impact will be in non-critical structures but will provide the same gains in weight and performance of continuous fiber. Certification of recycling process and short fiber preforms/prepreg can lead to use in performance critical components on DoD platforms. An additional benefit of the short fiber architecture is in-plane stretch, which enables conformity to complex geometries avoiding manufacturing scrap from complex ply patterns. The approach will reduce part and lifecycle cost.

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Points of Contact

Principal Investigator

Dr. Dirk Heider

University of Delaware

Phone: 302-831-8898

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